This section discusses types of existing formula parsing systems, past and present. These systems are possibly components of some larger existing system. Their ability to process input ranging from neat typeset print to sloppy handwritten entry is discussed.

The goal of a formula parser is to start with a set of recognised symbols, and return a description of the formula that they represent. Blostein and Grbavec give a good overview of the categories of existing techniques for parsing mathematical formulae.

give a good overview of the categories of existing techniques for parsing mathematical formulae.

- Modified Grammars
- Box Languages
- Projection Profile Cutting
- Procedurally Coded Math Syntax
- Stochastic Grammars
- Graph Rewriting
- Data Driven and Knowledge Driven Modules